Northcreek Okara Revision Question

[mevaniuck]

I am interested in the SDS Okara which is a modification of the North Creek Music's Okara. The drivers it uses are the Vifa's P13 and XT25.

Instead of the original 2-way design I would like to try an MTM configuration. As far the the cabinet goes I can always build the Eska which is an MTM mini tower.

If I use a proven crossover design like the SDS Okara ( woofer , tweeter ) which uses an active crossover what changes do I have to make to the crossover values if I run 2 P13's in an MTM config.

Sorry if this seems like a noob post but my knowledge of crossovers is limited and I need to build from a established project on the web. I have the P13's for the project but have found no P13 based MTM's on the web except for the Ariel/ME2 but I am not running hi-end tube gear, just a regular off the shelf receiver.


Mike

[Hugo Rodriguez]

For me it is very difficult to design a new crossover for the MTM version you are looking for, because in the new one you will have two woofers in parallel. The problem involves measurement equipment and ...

yes! an anechoic chamber.

I will recommend you a trick, that it is not to much difficult, but could be judged as out of law. Such is a 2 1/2 way version, that means that you will connect the second woofer in parallel with the first one, but having a coil between each other, in order to have the parallel only at the lowest end of the spectrum. You can try with values from 1 mH to 3 mH, and select it by listening tests.

You will get a lot of bass, because at the lowest end the amplifier will see about a 4 ohms impedance, that will rise to the higher frequencies.

It is just a sugestion. You decide if it is worth to try.

Regards,

Hugo

[clm811]

I built 3 pairs of MTM minimonitors using P13WH008's and XT25's
about 4 years ago. The sound is quite good and they measure flat within +/_ 2dB.

See post in other thread:

The Ariel with new tweeter

The bass in a ported enclosure is insufficient for full range use,
so I use subs with each channel.

The SDS Okara revision is good, too for when high output is
not needed.

-chas

[mjsummers]

I built the North Creek Eska mini-towers plus the Eska center channel -- all in MTM configuration -- as well as the North Thunder sub over a period of a year. They sound unbelievable and are well worth the effort, especially if your room requires you to place these near the walls (where they actually provide better sound than alternative placements).

I cannot answer your technical question about the crossovers. But, if you plan to buy North components for the build, I would strongly suggest that you directly contact George Short who owns/runs North. He is THE crossover guy in audio and really supports DIYers. Over my build period, I bugged him often (usually via email) and he always answered my questions himself and generally within 24 hours.

If you want more details, let me know. Have fun!